There has been renewed interest in the chemistry of cubane since some of its derivatives, particularly nitrocubanes, have shown promise as high density energetic materials. The exceptional strain energy (166 kcal/mol) and rigid framework of the cubane skeleton also suggest promise for the use of substituted cubanes in the fields of pharmaceuticals and polymers (Chemistry of Energetic Materials; Ed., G. A. Olah; D. R. Squire; Academic Press, Inc., San Diego, Calif., 1991. Also see Carbocyclic Cage Compounds; Ed., E. J. Osawa; O. Yonemitsu; VCH Publishers, Inc., New York, N.Y., 1992).
Although several synthetic methods have been applied for the synthesis of halogenated cubanes, however, direct halogenation of the cubane systems bearing electron-withdrawing substituents such as carboxy or nitro groups has not been documented.
The present report described the photochemical synthesis of halogenated polycarboxycubanes from simple carboxycubanes and an oxalyl halide.